This invention relates generally to the field of telephony, and more particularly to an improved form of test shoe used by service personnel to determine the existence of defects in individual subscriber circuits. Devices of this general type are known in the art, and the invention lies in specific constructional details which permit the use of the shoe in connection with specialized equipment employed by telephone operating companies.
Individual subscriber circuits are normally interfaced for protection and switching upon a connector block, the block being one of many carried by an individual telephone main frame. It is desirable to have the individual subscriber circuits available for testing at the main frame location, and for this purpose many connector blocks have an adjacent test field offering test points accessible to manually engaged probes. To save valuable space on the main frame, more recently developed connector blocks have provision for mounting protector modules, one for each circuit which serve the purpose, not only of protecting the telephone office equipment from current and voltage surges on the subscriber line but of disconnecting the subscriber line, where required, by partially withdrawing the module to a so-called detent position, wherein it remains engaged with the connector block, but opens the subscriber circuit.
In an attempt to provide greater available subscriber line density on the block, it has also become common to eliminate the field, and provide test points on the outer surface of the protector module casing on either side of the manually engagable handle. The test points are accessed as a group by engagement with a test shoe having recesses in an oprative face thereof to clear the handles on the modules, as well as spring loaded pins which penetrate the openings in the outer end walls of the casing to contact test points positioned therebeneath. The shoe is normally clamped to the block to permit a group of subscriber circuits to be tested in serial form, and when a test cycle is completed, the shoe is removed to be repositioned with respect to the block for the subsequent testing of other subscriber circuits on that block.
Individual telephone operating companies use test equipment of different types and capacities. Some of the equipment provides testing functions which require the opening of the subscriber circuit during the testing procedure, and in such cases, it is necessary to close the circuit after completion of testing in order to restore service to the subscriber. The opening of the circuits is most conveniently done by moving the protector module from fully engaged to detent position as mentioned hereinabove. However, when the conventional test shoe is locked in position on the block, the handle members of the individual protector modules are not accessible. Further, the conventional test shoe does not have recesses in the operative face thereof to accomodate protector modules in detented (or extended) position, so that to open the subscriber circuits, it is necessary to remove the test shoe from engagement with the block. Once this is done, the test can no longer be performed using the test shoe as an interface device.